Minor bug. Not on test, on the main server.
When you move a stack of items while said stack is the source of all of the materials in a stack on the tailoring crafting popup, during a crafting action, the stack count in the crafting popup does not update when the crafting action is complete.
However, when you try to simply click craft again, the stack count in the materials section reduces to the proper value of zero. The decrementation of the stack is occurring, it's just not visible until you try to activate another crafting action. If you try to move items into the crafting materials window on top of the existing bogus stack count, the stack count in the materials section corrects itself to zero, the items in inventory do not decrement, and you have to do the move action again.
Nothing game breaking here, just irritating if you are trying to sort inventory while crafting.